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Member postings for Robin Graham

Here is a list of all the postings Robin Graham has made in our forums. Click on a thread name to jump to the thread.

Thread: GAS PRESSURE
16/01/2010 21:27:29
What gas? Liquid propane would be around 130 psi (~9bar) and liquid butane around 40 psi (~2.5 bar) at that temp.
Regards, Robin
Thread: Choice of small milling machine
06/01/2010 21:47:17
Hello, apologies for deserting this thread for so long, 'real life' (ie daughter back from uni) somehow intervenened... 
 
Many thanks to all who have offered comments/advice. 
 
Martin W - it sounds as if the constraints you are working under are similar to my own and I much appreciate  you taking the time to pen such a detailed response.   I would be very interested to hear how you find the upgraded WM-14 . My email is orbin at tiscali dot co dot uk, but I suspect others reading would also be interested, so maybe better to post here if you have time?
 
I think, from what I have read here and elsewhere, I'm going to go for the upgraded WM-14, and for tooling a half- decent vice to start with.

Meyrick, off topic, but thanks for your advice about modifying drill bits for brass on my earlier thread -  I did as you suggested and was astonished at how much difference a minute change in geometry made to performance.  The cheapo bits (which were really just chewing their way through before) now cut clean and (reasonably) true without grabbing.
 
Regards, Robin.
 
 
27/12/2009 19:37:08
  Hello Peter H, many thanks for your helpful comments re the mini-mill.  I had been a bit worried about backlash on the fine-feed arrangement but from what you say it seems that this may not in practice be a problem.  The capacities/masses of the two machines seem broadly similar - perhaps it will come down to economics.  Certainly the money saved by going for the mini-mill would be useful for tooling - I gather that milling machines are even more ruinous than lathes in this respect.
Regards, Robin
26/12/2009 20:29:58
Hi Ian S C , thanks for your suggestions.  Although ARC don't do the Seig X2 anymore, they can be had (Axminster sell them in the UK) but the reviews on the Axminster site and elsewhere say that they are (a) very noisy and (b) prone to problems with the drive train gears shearing. Although both those defects can be mitigated by replacing the gears with a belt drive, the basic specs of the X2 don't seem as good as the Weiss (ie Warco, Chester, Amadeal up here) machines.  Food for thought though.
Thanks again, Robin.
23/12/2009 20:55:27
Hmm. I'm beginning to suspect that rigidity might be a desirable characteristic in a milling machine .  Sadly, I just can't accommodate anything much above 60kg as it has go in an upstairs room.  However, thanks for pointing this up. To recap, when I started this thread I was trying to decide between  Warco's mini-mill and their WM14 and listed what I thought what I thought were the important differences, but failed to note that the mini-mill has a tilting column, while the WM14 has a tilting head. I guess the latter is the lesser abomination so far as compromising rigidity goes.  Though no-one has posted of  their experiences with the mini-mill for good or ill, I think I'll go for the WM14.  Thanks again, and Merry Xmas to all - off to reinforce roof rafters now in case Santa's been reading this.
Regards, Robin.    
22/12/2009 19:49:04
John and Meyrick, thanks for your advice re tooling.  At some point I shall need the capability of making non-right angle cuts, but I take the point that  for general use a tilting vice would compromise rigidity unneccessarily.  I shall go for a clamping set and swivel vice as recommended.  I don't think I've come across the term 'K-type' before though - can you elucidate Meyrick?
 Regards, Robin
 
21/12/2009 20:13:33
Many thanks all for your responses so far.  I confess I was rather surprised by the problems with the WM14 reported by Hansrudolf's correspondent as I had heard that Warco stuff was generally OK and that they were good to deal with.  There is a review of the machine at http://cign.org/wm14mill.html which mentions a few minor niggles, but nothing that drastic -  which seems to chime in with what the majority are saying here.
 
Martin  - I'd be most interested to hear how you get on with your machine when it arrives. As you presumably had the opportunity to 'twiddle' with various machines at Sandown I'd also be interested to know what considerations led you to your choice of purchase.
 
I have indeed looked at ARC's Sieg X3, which by all accounts is a very capable machine, but sadly it is just too big - the 60kg of the WM14 is at the top limit of what I can cope with.
 
I like Richmond's suggestion (and so does my wife!) that I should make my own tooling so far as possible - but can anyone advise on the best startup option for workholding?  I am thinking to go for a decent quality tilting vice, then make my own T-nuts, step blocks etc.  Does that sound sensible?
Thanks again, Robin.
 
 
 
 
 
 
20/12/2009 17:57:13
Hi. Having owned a small lathe for a 6 months or so, I have come to the (perhaps inevitable) conclusion that I need some sort of milling capability as well. I am looking at the Warco mini-mill (currently on offer at £410) and the Warco WM-14 (£635). Although the mini-mill has more X- travel, the sizes/masses/capacities of the two machines seem otherwise broadly similar. As far as  I can see, if I were to go for the WM-14 the extra cash would be buying me (a) a DRO on the Z-axis (b) 'precision taper spindle bearings' (no mention of bearings on the mini-mill in the catalogue, so I assume they are of lesser quality?) and (c) a more sophisticated arrangement for Z-axis movement - a rack-and-pinion driven quill and leadscrew driven headstock, compared with a rack-and-pinion headstock drive on the mini-mill.  I don't know if the WM-14 uses the same plastic drive gears as the mini-mill, which I gather can be a source of frustration.  I am sort of inclined to the WM-14 mainly because of (c) - I believe there is a lot of backlash in the mini-mill arrangement, which can be a problem,but I really don't know. Obviously I don't want to spend the extra unnecessarily -  if anyone with more (i.e any!) experience could advise, I'd be very grateful.
Regards, Robin.
Thread: Drilling problem - the sequel.
22/10/2009 20:41:27
Hi Chris, thanks for your welcome to QTAS. 'Tis too true.  I had a similar experience with taps/dies - having blown most of my start-up budget on the lathe, I went for a cheap (about 30 quid) set of dies and taper taps.  I then needed a bottoming tap for some reason and bought one-off from a 'proper' engineering supplies merchant (about a fiver for one tap). And then worried that I'd cut the core too big 'cause it slid through so easily...
 I'm attracted by your idea of modifying the cheapo drills, though I confess I don't quite understand your instructions, but shall think on't.
Regards, Robin.

22/10/2009 19:51:20
Thanks Rob - that's reassuring. I shall try clamping the quill somewhat as you suggest.  I was going at about 800 rpm - the lowest speed the machine offers is 500rpm.  Would that  still be fast by your standards?
Regards, Robin
22/10/2009 19:00:31
Hello. I picked up a set of Dormer drills (to replace the cheapo Screwfix set I had been using)  and a Rohm chuck and arbour (to replace those supplied with my Axminster drill press) at the Midlands ME exhibition last weekend.  Good Lord, what a difference! Apart from the fact that the drills cut so much faster and with far less effort than the old ones, I'm now getting parallel bores.  However...whilst drilling aluminium and steel is fine, if I try a smallish (4mm) hole in brass, after getting in about 1mm the bit decides it can do without my help and pulls in to the work for another 2-3mm on its own (noisily and at alarming speed!). Things then go normally for perhaps 0.5mm, then the same happens again and so on. At larger diameters (>6mm) the chuck actually pulls out of the spindle taper. Any ideas as to cause / remedy?
Regards, Robin.
Thread: Drilling problem
14/10/2009 21:48:37
Thanks again for all your advice - though some of it was way over my head.(4-facet sharpening. Eh? So much interesting stuff to learn!) I am now convinced that a decent set of drill bits is a necessary investment, and shall present my Case for Support to the to the purse-holder for urgent consideration.
Regards,Robin
10/10/2009 19:08:54
Many thanks all for your useful comments.  I had in fact set the table as square as I could left-to-right but there is a residual error of about 0.1mm in 100mm (ie about 0.06 degrees) fore-and-aft which I imagine can be corrected only by shimming somehow.
I tried the test for play which Jeff suggested and found that there is indeed significant 'wobble' - I could 'scribe a line' nearly 1mm long with the tip of the 8mm drill bit by grasping the chuck and pulling on it.  I then tried replacing the chuck and arbour (hope that's the right word - the thingy with B16/MT2 tapers on it) supplied with the press with those which  came with the lathe.  The play was reduced by an order of magnitude which suggests that the problem is with the chuck and/or arbour.
The drills I am using are from a cheap (about 7 quid) set of 19 which I bought years ago from Screwfix, so that might not be helping either.  My general experience of tooling so far is that it's very much 'you gets what you pay for'. Which prompts my next question... is it worth shelling out say 50 pounds for a set of Dormers?  
Thanks again for all your suggestions and general advice on making holes in metal,
Regards, Robin. 
09/10/2009 22:21:45
Thanks Chris, you are not being dense at all! I didn't drill in the lathe (which I knew should work) partly because I was trying out a different method just to see what would happen  and partly beacause I wanted to see what the (cheap) new drill press could do. I have no  background in mechanical engineering, so I'm still experimenting.
Your explanation  of the reason for the 'conical bore' makes good sense to me.
Thanks  again, Robin. 
09/10/2009 20:22:38
Hi, I have recently acquired a drill press (one of the smaller Axminster bench-mounted jobs) and today used it to drill  8mm through the axis of  a 1.5 inch long piece of 1.25 inch diameter round steel bar.  The procedure I adopted was to turn the bar to diameter in the lathe, centre drill whilst still in the chuck then transfer to the drill press for drilling through. I clamped the bar in a vice, aligned the centre-drilled hole in the workpiece with the drill bit as best I could by eye, tightened the vice to the table and chewed my way through.
The problem is that the resulting bore, whilst spot-on 8mm (as near as I can measure) at the 'exit hole', is around 8.5mm at the 'entry hole'.  Can anyone explain what is happening here?
Thanks in advance, 
Regards, Robin.   
 
Thread: Small Milling Machine
30/09/2009 21:04:34
Many thanks Phil and Peter for your responses to my post.  I think I'm veering towards the WM-14 - despite Peter's reassuring remarks, the idea of having to bash out bearings to change the gears scares me stiff. I'm very new to this - I've had a lathe for only four months, and have no background in engineering.  Perhaps I'll get down to the midland ME exhibition next month and see the machines 'in the flesh'.
Concerning the belt drive modification to the generic X2 mills suggested by Stewart Hart  (which I had been considering as a possibility for the Warco mini-mill) I guess that the kit he refers to is that offered by Stirling Steele. They have a video on their website showing how to use their kit to replace the gear train, and it seems far less daunting than the process Peter describes for replacing the gears - which makes me wonder if the differences between the Warco machine and the Sieg X2 are more than superficial.
Thanks again for your replies, and also to David Howorth for starting what (for me at least) is a very interesting thread.
Regards, Robin
 
29/09/2009 17:32:39
I am in a somewhat similar position to the OP and have read the above with interest - I had been considering the Warco mini-mill as well, but I'm a bit put off by hearing that it suffers from the notorious plastic - gear problem.  As a complete tyro I suppose I'm bound to shear the gears probably sooner rather than later and the process Peter describes for replacing them sounds rather daunting.  Also I have read that the gears are pretty noisy - not good for me as my 'workshop' is in the house.
 Has anyone any experience of Warco's WM-14 mill? It is a bit more expensive, but does come with 'an individual accuracy report' which might indicate that Warco have more confidence in the build quality.
Regards, Robin
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